Tank for fuel oil or other liquids

ABSTRACT

A double-walled tank is provided for the storage of fuel oil and other liquids and comprises a spaced inner and outer tank in accordance with known concepts. In the present disclosure the outer tank is made of asbestos-cement, preferably with continuously wound asbestos fibers.

United States Patent 1191 Diirkop Nov. 19, 1974 [54] K FOR FUEL OIL OROTHER LIQUIDS 2,814,406 11/1957 Marancik 220/18 x 2,925,190 2/1960Littleton 220/18 [75] memor- Herman" Burk, Bremen 3,151,416 10/1964Eakin et al 220/18 x Germany 3,489,311 1/1970 Folkerts et 61.... 220/9 R3,558,000 1/1971 McCann et al.... 220 18 x [73] Asslgnee gl gg g1219,537 4/1935 Pierce 220/63 R [22] Filed, June 17 1971 FOREIGN PATENTSOR APPLICATIONS 1,272,830 7/1968 Germany 220/9 A MN 154,052 240,2745/1965 Austria 220/18 1,243,375 6/1967 Germany 220 18 [52] US. Cl. 220/9A, 220/9 C, 220/9 M,

Examn 1erW1ll1am Prlce 511' 1111. C1... 8656 25/18, B65d 25/24, B65d51/18 -9 ShaP [58] Field 61 Search 220/9 R 18 63 R 9 A may, 4

220/83; 138/175, 174; 52/249 Bushnell & SS6,

[56] References Cited ABSTRACT UNITED STATES PATENTS A double-walledtank is provided for the storage of 683,517 10/1901 Stout 217/1 fuel Oiland other liquids and comprises a Spaced inner 1,157,675 10/1915 Caskey220/18 and Outer tank n a ordan with known concepts. In 1,251,830 l/l9l8Siegfried 220/9 A the present disclosure the outer tank ismade of asbe-,ll9 5/l932 Vanderwall-.. 220/l8 stos-cement, preferably withcontinuously wound as- 2,263,292 11/1941 Edwards l38/l 74 bestos fibers2,382,171 8/1945 Pomykala 220/18 x 2,467,999 4/1949 8 Claims, 6 DrawingFigures Stephens 138/174 X 1 TANK FOR FUEL OIL OR OTHER LIQUIDS It isknown to construct tanks for fuel storage and the like which are to beburied in the ground of doublewalled construction, or stated otherwise,of spaced inner and outer tanks. Sensing means is provided between thetanks operable, for example, according to pressure changes between thetanks to detect leakage of liquid into this space.

Liquid may leak from the internal tank due to the corrosion or otherreasons, while ground water or other liquids in the ground may seepthrough the outer tank in the event of any corrosion or damage thereto.In accordance with some prior art uses both the inner and the outer tankare made of steel, and the susceptibility to corrosion is obvious. Otherconstructions are known in which the outer tank is made of steel forphysical strength and protection, while the inner tank is made fromplastic materials reinforced with glass fibers. It is also known tosubstitute an outer concrete tank for the steel tank mentioned above. Itis common practice to provide a negative pressure between the two tankswhich is measured continuously by a suitable sensing device. Anyincrease in pressure in the space between the two tanks will cause thesensing device to actuate a warning signal. Alternatively, sensingdevices may be placed between the tanks at the bottom thereof to reactto the presence of moisture at this location.

Double-walled tanks by their very'nature are more expensive than simple,single-walled tanks. Not only are subterranean tanks subject tocorrosion, but they are also subject to physical damage duringtransportation from the factory to the construction site. Furthermore,they often must withstand a substantial external pressure when buried inthe ground, and under some circumstances the water table in the groundmay cause the tanks to float if they are only partially filled.

not entirely solve the problem since such coats are easily damaged. Theuse of plastics for the outer tank has not heretofore proved fullysatisfactory. Unless glass fiber reinforcement is used throughout, theplastic material is not strong enough, and the use of glass fiber raisesthe manufacturing cost, often to a prohibitive level. In any event, theuse of plastic for the outer tank results in a sufficiently light weighttank that special anchors must be used to preclude the tank from heavingor floating on the ground water. Rendering the anchoringsresistantagainst corrosion also significantly raises costs. a

The use of concrete for construction of the outer tank overcomes theproblem of corrosion, and also overcomes the problem of floating onground water. on the other hand, concrete tanks are easily damaged byphysical shock, and are so heavy as to increase installation costs to agreat degree. Due to the risk of physical damage, concrete tanks must beinstalled slowly and with a great deal of labor, thus raising the costof installation significantly. Concrete tanks are so heavy that they canbe installed only with the use of special cranes which are costly andwhich are available only in certain cities. The use of such craneselsewhere requires expensive transportation to a job site. Furthermore,the great weight of concrete tanks renders shipping thereof from thefactory to the job site expensive.

In accordance with the present invention, the problem of constructing atank for underground storage of fuel oil and the like which is resistantto corrosion and which is reasonably-inexpensive to fabricate andinstall has been solved.

In accordance with the present invention, the outer tank is made ofasbestos-cement, preferably with the asbestos fibers continuously wound.The outer tank is formed as a more or less cylindrical tube having endcovers joined thereto in physically strong and leakproof manner. Theinner tank may be of any known construction, preferably of plasticmaterial, while a warning device is provided between the tanks toactuate an alarm when any liquid enters the space between the tanks.

An outer tank of asbestos-cement can be placed directly in the groundwithout danger of corrosion. Due to the strength of the outer tank itweighs much less than a concrete tank, most particularly because thethickness need not be nearly so great.-Nevertheless,-the tank issufficiently heavy that it will not float in the subterranean groundwater, even when the tank is empty. Hence, no additional anchoring isrequired. The weight strikes on an ideal compromise between the toolightweight of plastic tanks and the too heavyweight of conventionalconcrete tanks, whereby transportationand installation difi'iculties donot arise, nor do problems of floating of the installed tanks. v

In the preferred embodiment of the invention the tank end pieces or lidsare formed of at least two asbestos-cement plates each, joined attheirconfronting faces, preferably by' a suitable adhesive. The resultingstructure is an asbestos-cement plate having portions of respectivelylarger and smaller diameter with the smaller diameter portion fittingwithin the wall of the outer tank, and the portion of the largerdiameter butting against the end of the outertank wall. Preferably theasbestos fibers of the two plates fonning a lid are radially arrangedwith the fibers of the adhesively joined plates being offset from oneanother arcuately by about ninety degrees. The lids are secured to theend of the outer tank by means of screws extending axially through thelids and into dowels or other screw receiving means installed in theouter tank wall. In addition, there are preferably radially directedscrews passing through the outer tank wall and threaded into dowels orthe like in the lids.

In addition, a sealing material is used between the lids Q and the outertank walls, and this preferably is an adhesive material coating all ofthe contacting surfaces between each lid and the respective outer tankwall. In addition, a sealing tape preferably is disposed over the slitbetween the lid and the outer tank wall on the outside thereof. Suchtape preferably is made of a corrosion resistant material and isprovided with an adhesive, such as of the pressure sensitive type.

Further advantages and structural details of the present invention willbe apparent from the following description when taken in connection withthe accompanying drawings wherein:

FIG. 1 is a longitudinal sectional view through a double-walled tankconstructed in accordance with the principles of the present invention;

FIG. 2 is a'partial cross section through the tank as takensubstantially along the line IIII in FIG. 1;

FIG. 3 is a view on a greatly enlarged section showing a preferredembodiment of the connection between a lid and the outer tank;

FIG. 4 is a view similar to FIG. 3 showing another embodiment of theconnection between the lid and outer tank;

FIG. 5 is an enlarged longitudinal sectional view of a modification ofthe invention wherein the inner tank comprises a plastic film, the viewbeing'taken in the vicinity of the tank inlet and;

FIG. 6 is a modified form of this invention showing the tank with oneend wall thereof formed as an integral part.

A double-walled tank or container 1 comprises an outer tank 2 and aninner tank 3. The inner tank 3 preferably consists of a syntheticplastic which is reinforced with glass fibers. The inner tank isprovided with feet 4 or other spacers for maintaining a suitable spacebetween the outer surface of the inner tank 3 and the inner surface ofthe outer tank 2. The inner tank 3 is provided at the top thereof, andconveniently adjacent the center a protuberance through which a fillingtube 6 and a control tube 7 lead to the inside of the inner tank 3. Themaximum diameter of the inner tank 3 measured across the feet 4 and theprotrusion 5 is somewhat smaller than the inside diameter of the outertank 2.

The outer tank 2, in accordance with the present invention, is formedessentially as a cylindrical tube comprising asbestos-cement. It has alength which is equal to or somewhat greater than the maximum length ofthe inner tank 3. At either end the outer tank 2 is closed by lids 8, 8,likewise made of asbestos-cement. The lids may be constructed as flatplates (viz, lid 8) or, in a preferred form, as shell-like orconcave-convex sections (viz, lid 8). The lids are secured to the tubeor sidewall of the outer tank 2 in a leak proof manner, preferably bythe use of an adhesive. As an alternative, one of the lids 8,8 may bemanufactured integral with the tube or sidewalls of the outer tank sothat it is thereafter necessary to install only one lid followinginstallation of the inner tank 3.

The outer tank is provided with a protuberance 9 substantially co-axialwith the protuberance 5 of the inner tank. The protuberance 9 preferablyconsists of a tube and is provided at its outer or free end with aflange which forms a sealing and attachment face for a cover plate 10which, upon removal, provides access to the interior of the outer tank2, and vents to the inner tank 3. The tube forming the protuberance 9preferably is adhesively secured to the sidewall of the outer tank 2.

Means is provided for ascertaining when any liquid enters the spacebetween the inner and outer tanks. In the present disclosure a pump 11is connected through a conduit 12 with the inner space between the twotanks. The pump removes a certain amount of air from this space, therebymaintaining it under negative pressure. Another tube or conduit 13passes through the plate 10 (as do the tubes or pipes 6,7, and 12) andhas connected 2. gauge or indicator 14 which indicates the pressureexisting in the space between the two tanks. In

addition, or alternatively, the tube 13 may be connected to an alarmactuator for operating a visual or audible alarm in the event thatpressure rises within the space between the tanks. As will beunderstood, the tubes 6,7, 12 and 13 pass tightly through openings inthe cover plate 10 so as to preclude leakage of air through the coverplate. In the event of any failure in the cover plate 10 or of failureto seal with the tubes passing therethrough, then there will be anindication of rising pressure in the space between the two tanks, andinspection will reveal the flaw where upon the plate can easily bereplaced without any significant expense.

With tanks having a capacity between roughly 500 and 2,000 gallons, ithas been found advantageous if the wall thickness of the outer tank 2 isabout an inch and a half, the wall thickness of the inner tank 3 isslightly less than 1/10 inch, and the spacing between the tank walls isabout ,45 inch.

It is particularly advantageous if the flat lids 8 of the outer tank arecomposed of several flat plates secured together by a suitable adhesive.Once such embodiment of a lid 8 is shown in FIG. 3, the lid comprisingtwo plates 20 and 21. The innermost plate 20 in this embodiment has anouter diameter just slightly smaller than the inner diameter of theouter tank 2, while the outer plate 21 has an external diameter which issubstantially the same as the external diameter of the outer tank 2.Accordingly, a rather large sealing face is created between theasbestos-cement tube and the asbestos-cement lids.

The two plates 20 and 21 have their asbestos fibers oriented in onedirection for each plate, and the plates are oriented relative to eachother so that the fibers in one plate are substantially perpendicular tothe fibers in the other plate. The plates are cemented or adhesivelysecured to one another in such relative position whereby the space 30between them is filled with the adhesive. In order to connect theasbestos-cement tube comprising the sidewall of the tank 2 to the lid,21 sealing mass is provided therebetween, and such sealing masspreferably comprises an adhesive. In addition to this, the parts aresecured together by screws including axially directed screws 25 passingthrough the outer plate 21 into the sidewall of the tank 2. Therearealso radially oriented screws 26 passing through the sidewall of thetank 2 and into the inner plate 20.

Each of the screws 25 and 26 preferably engages in a dowel received inthe corresponding sidewall or plate. Finally, a leak proof joint isfurther insured by the provision of sealing tape 31 which is passedaround the slit between the tube and the plate 21. This sealing tape 31resists corrosion and preferably is self adhering. It must also resistbeing desolved by or otherwise attacked by the liquid stored in thetank.

In a further embodiment of the invention as shown in FIG. 4, there arethree asbestos-cement plates 20, 21, and 22 of common outside diameterjoined to one another as by a suitable adhesive. All of the plates 20,21, and 22 are of a common outside diameter, and are secured to thesidewalls of the outer tank 2 by means such as screws 3, and preferablyalso sealing tape 31 wrapped around the outside of the slit between thesidewall and the inner plate 20.

In accordance with a further embodiment of the invention, the inner tank3 is formed as a plastic film which is connected to the outer tank 2 inthe manner shown in FIG. 5. The inner tank 3 has a lateral extension orprotrusion 35 corresponding to the protrusion 9 of the outer tank andgoes upwardly, extending first in a radial direction, and then aroundthe rounded upper end of the protrusion 9, and finally in an axialdirection. At the upper limit of the protrusion 9 there is attached arim 36 which in cross section is L-shaped secured by means such asscrews 37 to the vertical protuberance. The film of the protrusion 35 isintroduced into the slit between the rim 36 and the plate 10. Twoannular gaskets or washer like seals 40 and 41 grip the protuberanceagainst the upper flange of the rim 36.

A clamping ring 32 is provided to retain the film extrusion orprotuberance 35 against the protuberance 9 and comprises a clamping ring32 made either of synthetic material or a metal which is coated with asynthetic, and which presses the protuberance 35 resiliently against theprotuberance 9 of the outer tank 2.

As an alternative, it is possible that the leakage warning device mayconsist of metal anodes or similar parts arranged in the intermediatespace between the outer and the inner tank at the bottom thereof toindicate moisture arriving at that location. In order to insure that anysuch liquid will arrive in the region of such metal anodes, and also soas to facilitate cleaning of the inner tank, the inner tank and outertank are both inclined at a small angle from the horizontal. In thespace between the tanks at the bottom thereof there preferably isprovided a plastic grating (not shown) which allows a free flowing ofany liquid in the space until it reaches the deepest region of the tank.

In order to facilitate transportation of the tank and installationthereof, transportation belts (not shown) may be provided having eyeletstherein for receipt of hooks and the like for lifting of the tank. Suchtransportation belts and eyes need not be removed, but may be leftattached to the tank after its installation. FIG. 6 shows a modifiedform of this invention wherein the end wall 8" is formed as an integralunit of the outer shell 2.

The specific examples of the invention herein shown and described arefor illustrative purposes only. Various changes in structure will nodoubt occur to those skilled in the art, and will be understood asforming a part of the present invention insofar as they fall within thespirit and scope of the appended claims.

The invention is claimed as follows:

1. A container assembly comprising an inner and an outer tank adaptedfor under ground large capacity storage of fuel oil and other liquids,said outer tank being formed as a cylindrical tube made substantiallyentirely of asbestos-cement of a thickness to be self supporting of itsown weight and the weight of the inner tank, said tube including ends,at least one end being closed and sealed by a lid, said lid includingtwo plates of asbestos-cement secured together in face to face relationand having asbestos fibers in each plate oriented at substantiallyninety degrees relative to the fibers of the other plate.

2. A container as set forth in claim 1 wherein the asbestos-cement ofsaid tube comprises continuously wound asbestos fibers.

3. A container as set forth in claim 1 wherein one of the lids isintegral with said tube.

4. A container as set forth in claim 1 wherein at least one of the lidsis adhesively secured to the cylindrical tube.

5. A container as set forth in claim 1 wherein said lids form verticalend walls for said outer tank and at least one of said vertical endwalls is substantially flat.

6. A container as set forth in claim 1 wherein said lids form verticalend walls for said outer tank and at least one of said vertical endwalls is concave-convex configuration.

7. A container as set forth in claim 1 wherein the inner tank comprisesa plastic film.

8. A container as set forth in claim 1 and further including sensingmeans disposed between said tanks to sense the entry of liquid into thespace between said two tanks.

1. A container assembly comprising an inner and an outer tank adapted for under ground large capacity storage of fuel oil and other liquids, said outer tank being formed as a cylindrical tube made substantially entirely of asbestos-cement of a thickness to be self supporting of its own weight and the weight of the inner tank, said tube including ends, at least one end being closed and sealed by a lid, said lid including two plates of asbestos-cement secured together in face to face relation and having asbestos fibers in each plate oriented at substantially ninety degrees relative to the fibers of the other plate.
 2. A container as set forth in claim 1 wherein the asbestos-cement of said tube comprises continuously wound asbestos fibers.
 3. A container as set forth in claim 1 wherein one of the lids is integral with said tube.
 4. A container as set forth in claim 1 wherein at least one of the lids is adhesively secured to the cylindrical tube.
 5. A container as set forth in claim 1 wherein said lids form vertical end walls for said outer tank and at least one of said vertical end walls is substantially flat.
 6. A container as set forth in claim 1 wherein said lids form vertical end walls for said outer tank and at least one of said vertical end walls is concave-convex configuration.
 7. A container as set forth in claim 1 wherein the inner tank comprises a plastic film.
 8. A container as set forth in claim 1 and further including sensing means disposed between said tanks to sense the entry of liquid into the space between said two tanks. 